In order to efficiently use watermelon germplasm，this study analyzed and compared the genetic diversity of 24 main characters of 783 germplasms using genetic diversity indexes，coefficient ofvariation，and cluster analysis． The results showed that coefficient of variation(CV)values of the 13 quantitative characters ranged from 0.48%(The first female flowers node) to 54.82%(Single fruit weight)with an average of 23.79%. CV values of the 11 qualitative characters ranged from17.95%(Stem section shape)to 70.90%(Seed speckle color)with an average of 39.95%. The average diversity indexes( H′) of the quantitative characters was 2.08, and the average diversity indexes(H′) of the qualitative characters was 1.23. The characters with higher diversity indexes(H′)wereleaf longitudinal diameter(2.29)，leaf transverse diameter(2.24)，the fruit peel thickness(2.24)，fruit transect diameter(2.23), fruit development period(2.19), length between nodes(2.09), fruit longitudinal diameter(2.07), 100-seed weight(2.07), Seed per fruit(2.04). Based on clustering analysis of 24 phenotypic traits, the 783 collections, at the Euclidean distance of 25, could be divided into 2 broad headings：A was Citrullus lanatus；B was Citrullus colocynthis. The collections were further classified into 3 categories by cluster analysis at the genetic distance of 20: A1 was sp.vulgaris, A2 was sp.lanatus, B was sp.insipidus. at the Euclidean distance of 15，A11 was var.vulgaris, A12 was var.megalaspermus. A2 was var.capensis. Coefficients of variation(CV)and diversity indexes(H′) of watermelon phenotypic traits were high，indicating that watermelon have abundant variation and diversity.Euclidean distance 25 Can be used as a watermelon divide into species genetic distance，20 can be used as a watermelon divide into subspecies Genetic distance，15 can be used as a watermelon divide into varietas Genetic distance.